Oil cylinder extension testing device

The utility model discloses a device for testing the extension amount of an oil cylinder. The device comprises a stay wire type displacement sensor and a sliding part, a pull box of the pull wire type displacement sensor is fixed on the cylinder body of the oil cylinder; the sliding component is fixed at the bottom end of the oil cylinder lever, the pull wire end of the pull wire type displacement sensor is connected to the sliding component and can be automatically adjusted along with the position of the pull wire box, and a pull wire of the pull wire type displacement sensor is always kept parallel to the center line of the oil cylinder. That is to say, the stay wire length variation of the stay wire type displacement sensor is always consistent with the actual extension amount of the oil cylinder rod. According to the testing device, the function of automatically adjusting the position of the stay wire end is achieved in a constraint removing mode, and the testing device is suitable for measuring the relat